(1). Field of the Invention
This invention relates, in general, to a modular type receptacle unit or assembly useful in an electrical outlet, switch or junction box assembly. More particularly, the invention relates to an improved electrical outlet, switch or junction box assembly comprising, in its basic aspects, only two components offering quick connect/disconnect features between the outlet, switch or junction box and the cover plate unit. Further, the invention provides quick connect/disconnect features between an outlet box and the electrical receptacle or wall socket to be, or already, located therein.
(2). Description of the Prior Art
With the ever increasing costs for electrical work, and the general desire for improved efficiencies and greater time savings in installation and repair, efforts have been made heretofore to devise an electrical outlet wall unit for home and building electrical wiring which offers savings in such areas, compared to the conventional outlet unit. By conventional outlet unit is meant the widely used electrical outlet unit having a rectangular-shaped outlet box into the cavity of which a rectangular-shaped plug receptacle is mounted by screws so as to be relatively flush with the opening of the box and which opening is then covered by a face plate having openings for the electrical plugs in the receptacle and fastened by a screw to the receptacle. In some cases, the "face plate" comprises two components, i.e., a back plate or frame and a front plate fitting therein.
The conventional electrical outlet units have the disadvantage of being slow to assemble and disassemble, even after the outlet box itself has been installed on a wall stud or the like. This is due to the fact that such units require, in general, two distinct assemblies/disassemblies, necessitating the screwing in, or unscrewing, by the electrician of at least three screws. Furthermore, as such conventional units are made up of a number of different components, i.e., electrical outlet box, receptacle unit, face plate, and three threaded screws, there is the necessity of having all of such components together, at the instance of a particular installation, otherwise such unit cannot then be fully installed. Such a complete installation may, for example, be delayed until a screw is located to fasten the face plate to the plug receptacle. Those who are familiar with the assembly/disassembly of such conventional electrical outlet units are readily familiar with the frustrations caused in looking for a dropped screw fastener. Oftentimes, particularly in building construction, such a dropped screw cannot be readily located and a further screw fastener need be obtained, to complete the installation. In the event of such a happening, this further reduces the efficiencies in the installation of electrical outlet units and adds to the time involved in making the installation, resulting in increased labor costs. In commercial buildings, particularly, where numerous electrical outlet installations must be made, the problems associated with the use of such conventional electrical outlet units having mounting tabs for screw fasteners can be readily appreciated. Nevertheless, to a somewhat lesser degree, the same problems exist in residential housing.
A further problem in the use of conventional outlet units having vertically disposed mounting tabs or ears involves the manner in which the outlet boxes are usually installed. The outlet boxes are mounted by screws to a stud so that the open face of the box protrudes outwardly from the front edge of the stud about a 1/2 inch or so. This is so that when, for example, the dry wall is installed, the front edges of the outlet box will be flush with the outside planar surface of the dry wall. Nevertheless, these outlet boxes are often incorrectly installed e.g., they may not be truly vertical. In that case, the front of the outlet box will not be flush with the dry wall surface. Sometimes the thickness of the dry wall panels may vary slightly from one another. Thus, if the electrician installs the outlet box so that its front edge sticks out 1/2", this may provide an outlet box flush with the dry wall surface, in some cases, but not in others. These mounting problems may not be discovered, however, until the sheetrocker comes along later to install the dry wall. At that time, the sheetrocker must make the necessary measurements to determine the location of the cut-outs for the outlet boxes and then cut out the openings in the dry wall panel being installed, so that the dry wall can be attached to the studs. Where the outlet box is not vertical, or protrudes outwardly more than the thickness of the dry wall panel, or less than such thickness, this presents some difficulty to the electrician when he comes along later to fasten the wall socket with the screw fasteners provided with such assemblies, to the already mounted outlet boxes. The outlet box is mounted behind the wall and its orientation to the stud, hence its flushness to the dry wall surface, cannot then ordinarily be adjusted without taking down the wall. Thus, when the face plate is mounted to the plug receptacle, the result is, in the one case, a face plate that is not flush with the dry wall surface. Such a mounting is obviously undesirable in its appearance. In the other case, longer screws may need be obtained to complete the mounting.
In addition to the above difficulties, the manner of mounting the conventional outlet boxes reduces somewhat the efficiencies of the sheetrocker. This is due, in part at least, to the fact that the sheetrocker must cut out each opening in the dry wall for the outlet boxes as such are encountered. Otherwise, the dry wall panel cannot be fully installed. As a result, one job is interrupted while another is necessarily performed. It would be far more efficient and faster if the sheetrocker could install the dry wall without this interruption, coming along later after the installation and then, at one time, cutting out all the openings for the outlet boxes. Nevertheless, such an approach is not now possible with the conventional electrical outlet units.
The costs of labor for the installation of the conventional electrical outlet assemblies greatly overshadows, it is believed, the costs of the devices per se. Thus, a savings in installation costs can still be made even where such electrical outlet devices themselves may be somewhat more costly than the conventional electrical outlet unit. Exemplary of various prior attempts to address this and related problems with electrical units other than outlet boxes, e.g. switch boxes, junction boxes, etc. are shown in U.S. Pat. Nos. 2,934,590; 3,168,612; 3,185,760; 3,437,737; 3,885,852; and 4,059,328.
U.S. Pat. No. 2,934,950, which issued Apr. 26, 1960, is directed to an electrical outlet receptacle which can be installed without requiring the use of screws or similar fastening means. In general, the outlet receptacle comprises a rectangular-shaped box having an open front defined by top and bottom walls, along the front edge of which are provided elongated notches or slots each parallel to a respective front edge, a receptacle assembly, and a cover plate. The receptacle assembly is provided with resilient fastening clips at its top and bottom, each of which is provided with a lug which fits into a respective notch in the outlet box on assembly of the two members together. The cover plate is provided on its inner surface with outwardly extending brackets, each of which comprises a spring arm which, on assembly of the cover plate with the outlet box, is received into respective clips located on the receptacle assembly and are frictionally engaged therewith. Nevertheless, while the receptacle assembly and cover plate can be assembled with the outlet box without need for screw fasteners or a screw driver, the receptacle disclosed still suffers from at least some of the earlier mentioned problems. For example, the outlet box must be installed in a truly vertical manner; otherwise, the face plate will not be flush with the surface of the wall. Even so, however, the problem resulting from somewhat varying thicknesses of dry wall panels remains.
U.S. Pat. No. 3,168,612 discloses a mounting adapter for attaching an electric switch case and its associated snap action button actuator to a mounting plate. The mounting adapter, in general, comprises a flat, rectangular-shaped frame portion defined by spaced-apart side flanges and spaced-apart end flanges which, in turn, define a rectangular-shaped opening Integral with the end flanges and extending rearwardly through the opening are spaced-apart bracket elements at the ends of each of which is provided a forwardly extending spring element. These elements extend in planes extending outwardly from the respective planes of the brackets, the free ends of which are arcuately formed. Both lateral edges of each bracket element have an array of spaced apart slots or notches, each of the notches along one edge being aligned with a corresponding notch on the other edge. The switch assembly includes a metal plate having a pair of arms which engage with the switch case at each end and retain the plate thereon. At the juncture between the front face and each end of the switch case, the plate is provided with a pair of integrally formed lugs which are adapted to engage a corresponding pair of notches in the bracket, on assembly of the switch assembly with the mounting adapter. Thereafter, the combined adapter and switch assembly are passed through a rectangular shaped aperture or hole in the mounting plate until the side and end flanges of the adapter lie flat against the outer planar surface of the plate. Due to the outward spring tension exerted by the forwardly extending spring elements on the mounting adapter, the arcuate bowed ends of the spring elements are urged against the top and bottom edge of the aperture in the mounting plate. Thus, the mounting adapter is secured to, and can be removed from, the mounting plate, according to the patentee, by spring-like snap action. Although such a mounting adapter may provide for installation of a switch case in a wall plate without need for screw fasteners, there is believed to be no specific disclosure as to how the wall plate itself is fastened to the dry wall, or other wall member in which the switch case is located. If this is accomplished by the spring members being merely frictionally engaged with the top and bottom edges of the cut-out in the wall, then it seems that obtaining a good fit is quite problematic. The fit would depend, it seems, not only on the dimensions of the opening, but also upon which particular set of notches in which the lugs are located. Selection of the wrong notches could result, it seems, in the mounting adapter being either too tight for the cover plate to be pulled in flush with the wall surface, or too loose whereby the wall plate might not be held closely and flush against the wall surface. Either could result in a less than satisfactory installation and appearance. Moreover, there seems to be no way in which the vertical alignment of the mounting adapter can be adjusted in the event the wall cut-out is not properly oriented in vertical disposition.
U.S. Pat. No. 3,185,760 discloses means for mounting wiring devices such as electrical outlets and switch boxes. Thus, the conventional mounting strap for mounting a two apertured electrical receptacle having support tabs extending from each end thereof each having a screw opening therein is provided with integral rectangular-shaped tongues adjacent each of the tabs and located in opposing pairs extending outwardly from the mounting strap. Stirrup-like devices of U-shape construction, each having a cross piece extending across the back side of the receptacle and flat side members extending forwardly from the ends of the cross-piece, are connected at their ends to respective rectangular-shaped tongues provided on the mounting strap. The stirrup-like devices are each provided with spaced-apart sharp pointed tongues or barbs which are so disposed as to extend forwardly toward the mounting strap at about a 45 degree angle from the vertical. Thus, on pushing the receptacle combination into the outlet box, the device can only be pushed in so far, i.e. until the flat back side of the support tabs on the mounting strap come in contact with the wall surface. On insertion of the receptacle into the outlet box, the pointed tongues engage the top and bottom inside surfaces of the outlet box thereby holding the receptacle in position and resisting any effort to remove the receptacle from the outlet box. A customary wall plate is attached to the face of the receptacle, according to the patentee, by means of a screw entering the mounting strap as usual. Thus, this device not only requires modification of the conventional receptacle mounting strap, it also still requires use of a screw fastener for mounting the face or wall plate to the receptacle, as usually done with such a mounting strap. Furthermore, in the event the outlet box mounted on the supporting structure is not truly vertical or horizontally disposed, the push-in box mounting allows for no adjustment whereby the cover plate, when attached, will be vertically disposed, as desired, or made flush with the wall surface. A cover plate biased to a nonvertical disposition or not flush with the wall, even though such is slight, is undesirable as it is distracting in appearance.
U.S. Pat. No. 3,437,737, which issued on Apr. 8, 1969, is directed to a modular electrical outlet unit providing, perhaps, at least some possible ease in assembly/disassembly. Such a unit comprises a conventional outlet box, a back plate, and an electrical modular unit consisting of a unitary receptacle and a front plate. Connected to the modular unit at its rear is a vertically disposed back strap which has tension arms extending upwardly and outwardly toward the integral frontal plate. The arms each terminate with latching means which detachably engage with the upper and lower edges of the back plate which support the front plate at its top and bottom inside surface. Although the electrical module and front plate are somewhat readily assembled/disassembled by a snap-in arrangement, the back plate is still fastened, as conventionally done, by two screws to the outlet box. Thus, such an outlet unit still requires two separate assemblies in installation. Moreover, when an installation is being made, the problem of potentially missing, dropped or lost, screws remains. Perhaps more importantly, however, the electrical outlet unit allows only limited vertical alignment of the face plate, in the event the outlet box is not properly aligned vertically, or is installed on a supporting stud that is not truly vertical. Thus, it would appear that the back plate can only be adjusted in its vertical disposition, and then only in one plane, as a result of the horizontal slots provided in the back plate.
U.S. Pat. No. 3,885,852 discloses outlet assemblies in which, according to the patentee, a plug receptacle or switch unit can be assembled with the outlet box without the use of screws. Thus, the outlet assembly comprises a generally octagonal-shaped outlet box with which is assembled a plug receptacle of corresponding generally octagonal symmetrical shape having an integral, circular-shaped face plate attached thereto. The outlet box is provided with opposed pairs of lock fingers each of which project rearwardly from the front edges of the outlet box and inwardly, away from the inside surface thereof. The receptacle is provided with alternating lands or channels. On assembly of the two members together the lands are engaged by the inner ends of respective lock fingers, holding the plug receptacle securely in the outlet box when it is fully inserted into the box. The two members can be readily disassembled, however, by rotating the two members in opposite directions to one another whereby to cause the lands to disengage the lock fingers, moving off the lands into respective channels whereby the lock fingers no longer hold the plug receptacle in the outlet box. The plug receptacle may then be readily withdrawn from the outlet box. Although the outlet assembly disclosed appears to lend itself to more universal use, e.g. with plug receptacles, switch and telephone units, the construction is believed limited to the octagonal shape disclosed. Thus, while it may be possible to alter the shape of the face plate to other than circular shape, the shape of the outlet box and associated unit cannot be altered. To do so, it is believed, would change the manner in which the invention operates.
In U.S. Pat. No. 4,059,328, which issued Nov. 22, 1977, there is disclosed a mounting structure for attachment to, for example, an outlet box for the mounting of an electrical receptacle. The mounting bracket or structure comprises an elongated bottom defined by elongated edges each of which is turned up providing a curved in position for clipping engagement with a corresponding ridge provided on the receptacle to be assembled therewith. The end bracket is further defined by vertically disposed leg portions located at the ends of the bracket, each of which is provided at its end with a horizontally disposed lug in which is provided an aperture for a screw fastener and a clip portion for engagement with the outlet box. Thus, the electrical receptacle, which apparently is also of novel construction, can merely be pushed into clipping engagement with the outlet box, once the mounting bracket has been clip mounted on the outlet box. This box is provided with ears at each end thereof which match up with the apertures in the bracket lugs for screw fastening of a cover plate on the receptacle. Although various modifications of the mounting bracket is shown, it appears that apertures must be provided in the bracket to accommodate screws in order to fasten a cover plate on the outlet box, if such is desired. More importantly, however, it appears that with the novel bracket structure providing clipping engagement with, for example, an electrical plug receptacle, the plug itself must be of novel construction. Otherwise the two members cannot be held together. The bracket will not, it is believed, provide clipping engagement with the electrical plugs believed more conventionally now used.
Despite the above inventions as disclosed in the prior art, the conventional electrical outlet assembly earlier disclosed is still in wide use. The prior inventions are believed, in some cases at least, to be too expensive to justify their being used, even though certain advantages may be realized. In other cases, among other concerns, the installation of the outlet boxes still requires the use of screw fasteners for attachment of the frontal plates to the outlet box. Thus, there is still believed to be a need for an electrical outlet unit not only of relatively simple construction but one which offers ease and convenience in assembly/disassembly, attendant with reduced labor cost, particularly in the installation of electrical distribution systems in commercial buildings.